MIMICRY IN BUTTERFLIES 
Close Resemblances between Species May Be Protective, but Their Origin Is 
Difficult to Explain through Natural Selection 
A REVIEW 
HE theory of mimicry in butter- 
flies is one of the most attractive 
of the fascinating speculations 
which the early Darwinians put 
forward. It has long been part of the 
stock in trade of the text-book writer; 
but for a long time, too, there have been 
protests against the theory. 
R. C. Punnett, Professor of Genetics 
in Cambridge University, has now 
collected the evidence in a beautiful 
book, lucidly written and illustrated 
with colored plates.1. The work is a 
good example of the way in which many 
lines of biological investigation may be 
brought to a focus to throw light on a 
problem in evolution. 
“Mimicry,’’ Prof. Punnett says, “is a 
special branch of the study of adapta- 
tion. The term has sometimes been 
used loosely to include cases where an 
animal, most frequently an insect, bears 
a strong and often most remarkable 
resemblance to some feature of its 
inanimate surroundings. Many butter- 
flies with wings closed are wonderfully 
like dead leaves; certain spiders when 
at rest on a leaf look exactly like bird- 
droppings; ‘looper’ caterpillars simulate 
small twigs; the names of the ‘stick-’ 
and ‘leaf-’ insects are in themselves an 
indication of their appearance. Such 
cases as these, in which the creature 
exhibits a resemblance to some part of 
its natural surroundings, should be 
classified as cases of ‘protective resem- 
blance’ in contradistinction to mimicry 
proper. Striking examples of protec- 
tive resemblance are abundant, and 
although we possess little critical knowl- 
edge of the acuity of perception in birds 
and other insect feeders it is plausible to 
regard such resemblances as being of 
definite advantage in the struggle for 
existence. However, it is with mimicry 
and not with protective resemblance 
in general that we are here directly 
concerned, and the nature of the phe- 
nomenon may perhaps best be made 
clear by a brief account of the facts 
which led to the statement of the 
theory. 
ORIGIN OF THE THEORY 
“In the middle of the last century 
the distinguished naturalist, H. W. 
Bates, was engaged in making collec- 
tions in parts of the Amazonregion. He 
paid much attention to butterflies, in 
which group he discovered a remarkably 
interesting phenomenon. Among the 
species which he took were a large 
number belonging to the group Itho- 
miinae, small butterflies of peculiar 
appearance with long slender bodies and 
narrow wings bearing 1n most cases a 
conspicuous pattern. When Bates came 
to examine his catch more closely he 
discovered that among the many Itho- 
miines were a few specimens very like 
them in general shape, color and 
markings, but differing in certain ana- 
tomical features by which the Pierinae, 
or ‘whites,’ are separated from other 
groups. Most Pierines are very differ- 
ent from Ithomiines. It is the group 
to which our common cabbage butterfly 
belongs and the ground color is generally 
white. The shape of the body and also 
of the wing is in general quite distinct 
from what it is in the Ithomiines. 
Nevertheless in these particular districts 
certain of the species of Pierines had 
departed widely from what is usually 
1 Mimicry in Butterflies, by Reginald Crundall Punnett, F.R.S., Fellow of Gonville and 
Caius College, Arthur Balfour Professor of Genetics in the University of Cambridge. 
University Press, Cambridge (Eng.), 1915. 
price 15 shillings. 
Pp. 188, 
463 
